选择正确的替换词。

1. We have been friends for ten years.

A. since ten years              

B.ten years ago

C. since ten years ago          

D.ever since

2.I waited here for one and a half hours.

A. an hour and a half  

B. an hour and half  

C. half an hour  

D. a half and one hour

3. I have been collecting stamps for several years.

A. a little    

B. many      

C. much      

D. a few

4. More than twenty students come to school on foot in our class.

A. Less than    

B. Much than  

C. Over        

D. Around

5. Mom stores all the meat in the fridge , or it will go bad.

A. keeps      

B. lies        

C. has        

D. collects

下列选项中，哪一项是彩色多普勒能够检查心脏大血管的征象( )。

A．血流方向
B．血流性质
C．血流速度
D．血流范围
E．以上都对